Upper Darby, Pennsylvania 

May 1954 

Surface Sterilieation 

Of Hybrid Poplar Cuttings 

Fungus diseases of hybrid poplars aay be spread by 

spores that lodge in the resinous coating of buds of dormant 

cdttings, and in the lenticels. Surface sterilization by 

dipping the cuttings in fungicides was tested to determine 

whether such treatment would prevent the germination of 

spores of the canker-producing fungi Septoria rnusiva and 

Dotkichiea populea and the leaf-blotch fungus Septotinia 

populiperda . , 

Dormant cuttings of selected hybrid poplar clones 

were sprayed with a water suspension of mixed spores of the 

three fungi. After a short period of storage at 40' F. the 

cuttings were dipped in the test fungicides, then wrapped in 

waxed paper, and stored for periods af 1 to 3 weeks. Buds 

and lenticels were then selected at random from cuttings of 

each clone and were cultured on artificial agar medium. Buds 

and lenticels from untreated cuttings were similarly cultured as controls. 

The following fungicides were tested: Chlorox, Bordeaux mixture, Ferbam, Dithane 278, Captan, CRAG 3W, CRAG 

531, CRAG 5400, Dowicide G, Dow formation ML37, Dow formtiop M138, Ceresan M, Semesan, and corrosive sublimate 

(mercuric chloride). 1 

Effect Of Treatments 

On Fungus Spores 

Only three of the fungicides--mercuric chloride, 

Ceresan M, and Semesan--proved effective in decreasing or 

* 

'~ention of these commercial products is not to be 

construed as endorsement of them by the Forest Service or 

the Department of Agriculture. 
- ,- I 

preventing ?emination of the parasitic fungi., spores as well 

as Chose of the saprophytic fungi. The treatments with these 

fungicides were as follows; 

1. Mercuric chloride: 5% solution in 7% alcohol. The cuttings were dipped 4 seconds, wrapped in waxed paper, and 

stored at 40° F, until cultured. 

2. Mercuric chloride: 5% s~lution in 7% alcohol. The cuttings were dipped 4 seconds, wrapped, and stored at 

400 F. for 2 weeks. They were then rinsed thoroughly in 

running water, wrapped, and stored until cultured. 

3. Ceresan M: 2% suspension in water, The cuttings were 

dipped 4 seconds, aired 5 hours at room temperature, 

wrapped, and stored at 40' F. until cultured. 

4. Semesan: 1% suspension in water. The cuttings were 

dipped 15 to 20 minutes, wrapped, and stored at boo Fa 

until cultured, 

The fungicidal effect of the treatments is given in 

table 1.2 Buds and lenticels mere rated as sterile if no 

fungus, either parasitic or saprophytic, developed fromthem, 

From the nonsterile buds a saprophytic fungus that is common 

on buds of various plants was isolated, but none of the parasitic fungi developed. These fungicides, therefore, are 

considered excellent for the surface sterilization of the 

cuttings l, 

Effect Of Treatment On Growth 

Of Cuttings In Greenhouse 

To test the effect of the fungicides on the growth of 

the cuttings under greenhouse conditions, dormant cuttings 

of each clone, not sprayed with fungus spores, were dipped 

in the fungicides, wrapped, and stored. When the buds and 

lenticels of the sprayed cuttings were cultured, the unsprayed cuttings were planted in sand in. a greenhouse. Onehalf iach was cut from each end of the cuttings before 

planting. Untreated cuttings were also planted as checks. 

No serious toxic effect occurred op any of the treated cuttings planted in the greenhouse. Those dipped in the 

;?Waterman, A. M., and Aldrich, K. Fo Surface sterilization of poplar cuttings. U. $ . Dept . Agr. Plant Dia. 

* Rptr. 36 (5): 203-207. 1952. 

Waterman, A. M., and Aldrich, Ko F. Additional information on the surface sterilization of poplar cuttings. 

U. S. Dept. Agr. Plant Dis. Rptr. 38 (2) : 96-100. 1954. 
mercuric chloride solution developed more slowly than the 

antreated cuttings used as checks. Since the clones selected 

for testing represented several combinations of parent species, clonal variations in the production of roots and 

shoots we re evident. However, .the growth of the cuttings 

treated with Ceresan M and Semesan equalled that of untreated cuttings of the corresponding clones. The results from 

the four treatments indicated, that mercuric chloride tended 

to retard growth and that Ceresan M or Semesan might be 

preferable for surface-sterilizing poplar cuttings. 

Table 1.--Fungicidal effect of treatments on spores on buds and 

in 1enticel.s of dormant hybrid poplar cuttings 

Mercuric chloride 

Treated cuttings were planted in a nursery plot at 

Beltsville, Md., to test survival and growth. The results 

of these tests are reported in Forest Research Note No. 33.